akkadotnet/akka.net

Port of Akka actors for .NET

Arjen Smits

@Danthar

Not familiar with the framework. But im guessing it works because of the common well known protocol namely HTTP ?

Jari Pennanen

@Ciantic

@Danthar yes, but if you send Something.Greet, it must send the name of the item also

not only the json

Zetanova

@Zetanova

@Ciantic Newton Json serializer includes the type into the payload

But i dont know how u will conect to akka system with a differnt "languge" that cant reference akka.remote assembly

Jari Pennanen

@Ciantic

@Zetanova apparently I can't, but someday when .NET Akka supports HTTP it maybe possible

looking now how to "curl in to Akka.io"

Zetanova

@Zetanova

write an warpper

with WebAPI and singularR and hosted with owin or IIS

it includes security too

there you can map the messages, handle unrelated commands like subscription/unsubscriptions connect/disconnect

and make versioning easy happen

its good for native apps too,

Zetanova

@Zetanova

singnalR has some support for different languages

Marc Piechura

@marcpiechura

@Ciantic if you refer to Akka.http, I wouldn't wait for it ;) it took 4 people and two years or so to build this on the jvm

Arjen Smits

@Danthar

I do think that a small abstraction layer between something like Nancy and Akka.net could go a long way

But even then you'd have come up with a communication protocol. And... well..... before you know it, your redefining something like the SOAP envelope :P

Bartosz Sypytkowski

@Horusiath

@Ciantic Akka.Http is a web framework written on top of akka, not a transport layer for the cluster

@object thx, I'll try to take a look at it this evening

ilhadad

@ilhadad

Ok got rid of the ask pattern and instead used a message scheduler to time out. here is the new code and config on the sender side:
CODE:

            //Attempt to get a list of supervisors from the SupervisorRegistry
            SupervisorRegistryGetListRequest request = new SupervisorRegistryGetListRequest(Self);
            _SupervisorRegistry.Tell(request);

            var timeout = Context.System.Scheduler.ScheduleTellOnceCancelable(1000, Self, new SupervisorRegistryGetListEvent(request, null, false), Self);

            Receive<SupervisorRegistryGetListEvent>(e => {

                if(e.Success)
                {
                    _logger.Info("{0} Received supervisor list.", Self.Path.ToStringWithAddress());

                    timeout.Cancel();

                    // Save the list for internal use
                    _AreaToSupervisorActor = e.ResponseGetList.SupervisorDictionary;

                    _logger.Debug("Actor {0} is Initialized, moving to Ready state.", _ActorType);
                    Become(Ready);

                }
                else
                {
                    _logger.Warning("{0} Cannot retrieve list of supervisors. Unable to initialize.  {1} retries.", Self.Path.ToStringWithAddress(), _FetchSupervisorListReties);

                    // retry the request and increase the timeout
                    _FetchSupervisorListReties++;

                    // Set up the timeout
                    timeout = Context.System.Scheduler.ScheduleTellOnceCancelable(1000*_FetchSupervisorListReties, Self, new SupervisorRegistryGetListEvent(request, null, false), Self);

                    // Send the request again
                    _SupervisorRegistry.Tell(request);

                }

and the config on the sender side:

akka {
                    # here we are configuring log levels
                    log-config-on-start = off
                    stdout-loglevel = DEBUG
                    loglevel = DEBUG

          // Define an Nlog logger for the Akka system
          loggers = ["Akka.Logger.NLog.NLogLogger, Akka.Logger.NLog"]

            actor {
              provider = "Akka.Remote.RemoteActorRefProvider, Akka.Remote"
            }

            remote {
                            log-remote-lifecycle-events = DEBUG
                            log-received-messages = on

            helios.tcp {
                                hostname = "127.0.0.1"
                                port = 8777
              }
            }

And here is the new config and code on the receiver side:

        private void HandleGetListRequest(SupervisorRegistryGetListRequest r)
        {
            ImmutableDictionary<MicroServices.Area,IActorRef> immutableDictOfSupervisorsActors = 
                _KnownSupervisorsActors.ToImmutableDictionary(kvp => kvp.Key, kvp => kvp.Value.SupervisorActorReference);

            Sender.Tell(new SupervisorRegistryGetListResponse(r.Requestor,immutableDictOfSupervisorsActors,r));

        }

                akka {
                    # here we are configuring log levels
                    log-config-on-start = off
                    stdout-loglevel = DEBUG
                    loglevel = DEBUG

          // Define an Nlog logger for the Akka system
          loggers = ["Akka.Logger.NLog.NLogLogger, Akka.Logger.NLog"]

          // Enables connectivity to the remote ActorSystemBridge
          actor {
              provider = "Akka.Remote.RemoteActorRefProvider, Akka.Remote"
          }

          remote {
            helios.tcp {
                port = 8888
                hostname = "127.0.0.1"
            }
          }

                }

@Horusiath I took out the cluster

Ok got rid of the ask pattern and instead used a message scheduler to time out. here is the new code and config on the sender side:
CODE

            //Attempt to get a list of supervisors from the SupervisorRegistry
            SupervisorRegistryGetListRequest request = new SupervisorRegistryGetListRequest(Self);
            _SupervisorRegistry.Tell(request);

            var timeout = Context.System.Scheduler.ScheduleTellOnceCancelable(1000, Self, new SupervisorRegistryGetListEvent(request, null, false), Self);

            Receive<SupervisorRegistryGetListEvent>(e => {

                if(e.Success)
                {
                    _logger.Info("{0} Received supervisor list.", Self.Path.ToStringWithAddress());

                    timeout.Cancel();

                    // Save the list for internal use
                    _AreaToSupervisorActor = e.ResponseGetList.SupervisorDictionary;

                    _logger.Debug("Actor {0} is Initialized, moving to Ready state.", _ActorType);
                    Become(Ready);

                }
                else
                {
                    _logger.Warning("{0} Cannot retrieve list of supervisors. Unable to initialize.  {1} retries.", Self.Path.ToStringWithAddress(), _FetchSupervisorListReties);

                    // retry the request and increase the timeout
                    _FetchSupervisorListReties++;

                    // Set up the timeout
                    timeout = Context.System.Scheduler.ScheduleTellOnceCancelable(1000*_FetchSupervisorListReties, Self, new SupervisorRegistryGetListEvent(request, null, false), Self);

                    // Send the request again
                    _SupervisorRegistry.Tell(request);

                }

and the config on the sender side:


akka {
                    # here we are configuring log levels
                    log-config-on-start = off
                    stdout-loglevel = DEBUG
                    loglevel = DEBUG

          // Define an Nlog logger for the Akka system
          loggers = ["Akka.Logger.NLog.NLogLogger, Akka.Logger.NLog"]

            actor {
              provider = "Akka.Remote.RemoteActorRefProvider, Akka.Remote"
            }

            remote {
                            log-remote-lifecycle-events = DEBUG
                            log-received-messages = on

            helios.tcp {
                                hostname = "127.0.0.1"
                                port = 8777
              }
            }

ilhadad

@ilhadad

How can I examine dead letters to see what's going on? Also how do I get the logger to give me more info as to the root issue? Any other suggestions?

Kris Schepers

@schepersk

Any idea when the new SqlServer persistence package will be available?

ilhadad

@ilhadad

@Horusiath I was able to subscribe to the event stream to pull the dead letters it seems the messages are arriving at the remote system but they are all landing in deadletters. Not sure how to figure out what's wrong by looking at the deadletters. Any suggestions?

Bartosz Sypytkowski

@Horusiath

@ilhadad either the message recipient is dead, was not created, or its address is wrong

@schepersk we'll talk about this probably on today's meeting

Kris Schepers

@schepersk

@Horusiath :+1:

ilhadad

@ilhadad

@Horusiath When I send the reply with an immutable dictionary embedded in it fails, however, when I send the reply with a null it works. I though maybe it was a message size issue but that did not work either. Any other ideas?

Bartosz Sypytkowski

@Horusiath

@ilhadad maybe message cannot be serialized/deserialized?

ilhadad

@ilhadad

I guess so. Is there a way to peek into this process?

Bartosz Sypytkowski

@Horusiath

var serializer = actorSystem.Serialization.FindSerializerFor(message);
var binary = serializer.ToBinary(message);

ilhadad

@ilhadad

Is there a way to decorate a property with an attribute that will force serialization?

ilhadad

@ilhadad

@Horusiath Thanks for your help - we figured it out. The issue is related to the serialization/deserialize process! As it turns out if you have a dictionary of some object the object must have a default constructor. If it does not somehow the deserialization process fails. We even tried sending the message without the default constructor and that too also failed. SO... a default constructor is needed. Painful!

Bartosz Sypytkowski

@Horusiath

@ilhadad strange, I've got a lot of messages without default constructors and I'm pretty sure it was never an issue

ilhadad

@ilhadad

@Horusiath It also seems that the immutabledictionary cannot be sent over the wire while a regular dictionary is not a problem. Wierd. Can I use a regular dictionary?

Bartosz Sypytkowski

@Horusiath

yes, unless you modify it after putting into a message. If you have that risk, simply do .ToDictionary() call to create a copy of it.

ilhadad

@ilhadad

ok thanks for all your help.

morioma

@morioma

To handle remote disconnection I did something like this

signalRSelection = Context.ActorSelection("akka.tcp://api@127.0.0.1:4545/user/signalr");
signalRSelection.Tell(message);

So, I am forcing a Context.ActorSelection before tell. I am thinking this should work although there could be performance issue.
However, this doesn't seems to work all the time. (It works the first time the remote disconnected).
Anyway to do this kind of if(disconneted){ connect(); }?
(I am aware the watch for Terminated method. However, I have trouble finding the right time to ActorSelection again, because the remote could be still not available. )

morioma

@morioma

(I tried Cluster too, however, a bug regarding cluster broadcast group is prevent me to use it).

Vagif Abilov

@object

I've read recommendations to be extra careful when choosing serializer for persistent actors, and it makes sense - nobody wants past events to become unreadable. So I am rethinking our persistence serializer choice - we switched to Wire after Akka.NET 1.0.7 came with a warning that JSON.NET will be obsolete, but I am becoming more in favour of plain JSON documents that we will always be able to retrieve and parse into some internal type. So I am a bit confused with these recent Akka warnings about switching to Wire. Should we really? What will be the consequences for using JSON.NET? Or should we just use a different lib to read/write JSON documents?

Bartosz Sypytkowski

@Horusiath

@object general advise here is to have separate serializers for inter-cluster communication and for persistence, as these two things have a different priorities. When it comes to JSON.NET - it's a nightmare for case of Akka.NET. It's very slow, has big memory footprint, and it's unreliable in many cases (especially F# data structures and some weird combinations of system.collections.immutable and surrogate mechanism).

Vagif Abilov

@object

@Horusiath so what would you recommend for persistence serializer to ensure long lifetime of encoded events? And if Json docs are OK what handles them better than JSON.NET?

Bartosz Sypytkowski

@Horusiath

it depends on you. Some people like to use json as format for event sourcing - I personally would choose it only when it has native support from database (i.e. postgres, mongodb, eventstore). Otherwise I would go for something schema-driven, like Protocol Buffers, MS Bond or Avro. But tbh it's a matter of personal opinion.

Vagif Abilov

@object

I see. I've been also looking at Protocol Buffers. And in case of Json ServiceStack seems to be quite fast. When it comes to language type support, I am drifting to a conclusion that we should say goodbye to fancy F# types as journal event types and instead use adapters (like some Scala Akka article suggests) to convert to representation close to serialization protocol.

Kris Schepers

@schepersk

Hmm, if a name my sql server persistence plugin something else then "sql-server", it doesn't seem to work.. Anyone else having this problem?

Kris Schepers

@schepersk

akka {
  persistence {
    journal {
      sql-server {
    class = "Akka.Persistence.SqlServer.Journal.SqlServerJournal, Akka.Persistence.SqlServer"
    plugin-dispatcher = "akka.actor.default-dispatcher"
    connection-string = "Data Source=(local);Initial Catalog=HelloClusterSharding;Integrated Security=SSPI"
    connection-timeout = 30s
    schema-name = Sharding
    table-name = EventJournal
    auto-initialize = on
    timestamp-provider = "Akka.Persistence.Sql.Common.Journal.DefaultTimestampProvider, Akka.Persistence.Sql.Common"
    metadata-table-name = Metadata
      }
    }
  }
}

this works..

but when I replace the "sql-server" with something else, it doesn't..

Kris Schepers

@schepersk

I'm trying to use a different sql server persistence for cluster sharding.
I have my sharding config set up like this:

cluster {
  sharding {
    least-shard-allocation-strategy.rebalance-threshold = 3
    journal-plugin-id = "akka.persistence.journal.sql-server"
    snapshot-plugin-id = "akka.persistence.snapshot-store.sql-server"
  }
}

but I would like to replace the "sql-server" name with, let's say "sql-server-sharding"

Damian Reeves

@DamianReeves

If I'm starting a new green field project with Akka and F#, should I start with Akka.FSharp or should I go right to Akkling?

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